For PIOS

Humpback whales. Current populations of whales have not reached a level that would sustain commercial hunting.
[Image courtesy of OAR/National Undersea Research Program (NURP); University of North Carolina at Wilmington]

Humpback whales. In addition to humpbacks, fin and minke whales were used in the study.
[Image courtesy of OAR/National Undersea Research Program (NURP); University of North Carolina at Wilmington]

Group of humpback whales feeding. Whale numbers in the North Atlantic rapidly diminished because of commercial hunting.
[Image courtesy of NOAA]